// MachineSet ensures that a specified number of machines replicas are running at any given time.
// +k8s:openapi-gen=true
// +kubebuilder:resource:shortName=ms
// +kubebuilder:subresource:status
// +kubebuilder:subresource:scale:specpath=.spec.replicas,statuspath=.status.replicas,selectorpath=.status.labelSelector
type MachineSet struct {
    metav1.TypeMeta   `json:",inline"`
    metav1.ObjectMeta `json:"metadata,omitempty"`

    Spec   MachineSetSpec   `json:"spec,omitempty"`
    Status MachineSetStatus `json:"status,omitempty"`
}

// MachineSetSpec defines the desired state of MachineSet
type MachineSetSpec struct {
    // Replicas is the number of desired replicas.
    // This is a pointer to distinguish between explicit zero and unspecified.
    // Defaults to 1.
    // +optional
    Replicas *int32 `json:"replicas,omitempty"`

    // MinReadySeconds is the minimum number of seconds for which a newly created machine should be ready.
    // Defaults to 0 (machine will be considered available as soon as it is ready)
    // +optional
    MinReadySeconds int32 `json:"minReadySeconds,omitempty"`

    // DeletePolicy defines the policy used to identify nodes to delete when downscaling.
    // Defaults to "Random".  Valid values are "Random, "Newest", "Oldest"
    // +kubebuilder:validation:Enum=Random,Newest,Oldest
    DeletePolicy string `json:"deletePolicy,omitempty"`

    // Selector is a label query over machines that should match the replica count.
    // Label keys and values that must match in order to be controlled by this MachineSet.
    // It must match the machine template's labels.
    // More info: https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#label-selectors
    Selector metav1.LabelSelector `json:"selector"`

    // Template is the object that describes the machine that will be created if
    // insufficient replicas are detected.
    // +optional
    Template MachineTemplateSpec `json:"template,omitempty"`
}

// MachineSetDeletePolicy defines how priority is assigned to nodes to delete when
// downscaling a MachineSet. Defaults to "Random".
type MachineSetDeletePolicy string

const (
    // RandomMachineSetDeletePolicy prioritizes both Machines that have the annotation
    // "cluster.k8s.io/delete-machine=yes" and Machines that are unhealthy
    // (Status.ErrorReason or Status.ErrorMessage are set to a non-empty value).
    // Finally, it picks Machines at random to delete.
    RandomMachineSetDeletePolicy MachineSetDeletePolicy = "Random"

    // NewestMachineSetDeletePolicy prioritizes both Machines that have the annotation
    // "cluster.k8s.io/delete-machine=yes" and Machines that are unhealthy
    // (Status.ErrorReason or Status.ErrorMessage are set to a non-empty value).
    // It then prioritizes the newest Machines for deletion based on the Machine's CreationTimestamp.
    NewestMachineSetDeletePolicy MachineSetDeletePolicy = "Newest"

    // OldestMachineSetDeletePolicy prioritizes both Machines that have the annotation
    // "cluster.k8s.io/delete-machine=yes" and Machines that are unhealthy
    // (Status.ErrorReason or Status.ErrorMessage are set to a non-empty value).
    // It then prioritizes the oldest Machines for deletion based on the Machine's CreationTimestamp.
    OldestMachineSetDeletePolicy MachineSetDeletePolicy = "Oldest"
)

Error: marker `MachineSetTemplateSpec` not found

// MachineSetStatus defines the observed state of MachineSet
type MachineSetStatus struct {
    // Replicas is the most recently observed number of replicas.
    Replicas int32 `json:"replicas"`

    // The number of replicas that have labels matching the labels of the machine template of the MachineSet.
    // +optional
    FullyLabeledReplicas int32 `json:"fullyLabeledReplicas,omitempty"`

    // The number of ready replicas for this MachineSet. A machine is considered ready when the node has been created and is "Ready".
    // +optional
    ReadyReplicas int32 `json:"readyReplicas,omitempty"`

    // The number of available replicas (ready for at least minReadySeconds) for this MachineSet.
    // +optional
    AvailableReplicas int32 `json:"availableReplicas,omitempty"`

    // ObservedGeneration reflects the generation of the most recently observed MachineSet.
    // +optional
    ObservedGeneration int64 `json:"observedGeneration,omitempty"`

    // In the event that there is a terminal problem reconciling the
    // replicas, both ErrorReason and ErrorMessage will be set. ErrorReason
    // will be populated with a succinct value suitable for machine
    // interpretation, while ErrorMessage will contain a more verbose
    // string suitable for logging and human consumption.
    //
    // These fields should not be set for transitive errors that a
    // controller faces that are expected to be fixed automatically over
    // time (like service outages), but instead indicate that something is
    // fundamentally wrong with the MachineTemplate's spec or the configuration of
    // the machine controller, and that manual intervention is required. Examples
    // of terminal errors would be invalid combinations of settings in the
    // spec, values that are unsupported by the machine controller, or the
    // responsible machine controller itself being critically misconfigured.
    //
    // Any transient errors that occur during the reconciliation of Machines
    // can be added as events to the MachineSet object and/or logged in the
    // controller's output.
    // +optional
    ErrorReason *common.MachineSetStatusError `json:"errorReason,omitempty"`
    // +optional
    ErrorMessage *string `json:"errorMessage,omitempty"`
}